1. Field of The Invention
This invention concerns the remote control of appliances, such as ceiling fans, and/or associated lighting by transmission and reception of radio frequency signals containing control information, and more particularly a radio frequency, remote controller featuring pulsed bursts of r.f. carrier signal, wherein the position of the pulses in time convey the information for controlling the fan and/or associated lighting.
2. Description of Related Art
The remote control of business and home appliances, particularly ceiling fans and companion lighting, has become increasingly more popular. Such features as variable fan speed, fan reversibility, light intensity adjustment, and decorative appearance have made the ceiling fan and companion light a sought after addition to households and work environments. Further, these popular features have been made even more attractive with the advent of controllers that permit the user to vary the fan and light functions at a distance and without the need for manipulating a pull chain or string unattractively hanging from the fan or light.
However, there have been drawbacks associated with certain forms of remote control. For example, remote control by infrared or ultrasound suffer from "line-of-sight" limitation. Particularly, these forms experience signal interruption in the presence of physical obstructions such as walls, floors, etcetera, or even the blades of the fan itself. Additionally, these approaches are susceptible to interference from "noise", e.g., background light and sound, which may cause false control of the system.
Still further, the technique of power-current modulation, while referred to as remote control, is only a "qualified" form, in that it requires fixed mounting of the controller to the fan and lamp power circuits. As a result of the required fixed mounting, typically in a wall, the controller is rendered immovable, limiting flexibility of use and making the installation awkward and more expensive, and thus, less attractive.
On the other hand, however, remote control of appliances such as ceiling fans and associated lighting has been effectively accomplished with radio frequency (r.f.) signals. Physical objects such as walls, floors, and the like, while obstructions to light and sound forms of remote control, are transparent to r.f. signals. Further, an r.f. transmitter can be easily carried and manipulated by hand thereby permitting the operator freedom of use.
While r.f. controllers for combined ceiling fan and lighting fixtures have been known, problems have existed with them. For example, certain designs have been elaborate and complicated raising questions of cost and reliability. As an illustration, U.S. Pat. No. 4,538,973, issued Sept. 3, 1985, to Angott et al. describes an r.f. controller having a transmitter and receiver for controlling the fan motor and lighting circuits of a combined ceiling fan and light. However, in accordance with the Angott et al. design, the pulse counting technique proposed for processing the control data requires use of separate channels and frequencies to manage fan operation and light intensity. Accordingly, this multiplication of channels and frequencies results in an increase in system complexity and duplication of system components. As will be appreciated, increased complexity and component duplication raise cost and reduce reliability; results which are commercially unattractive.
Controllers, however, have been developed which permit control of multiple fan features as well as operation of associated lighting, with a single frequency and channel. MEDCO, Ltd. of Deer Park, N.Y., has offered a fan and light controller of digital designs which features a pulse-width modulation scheme in a single-channel system. The Medco controller permits control of fan activation, speed selection and direction as well as the intensity of associated lighting with a single modulated r.f. carrier signal.
Even in single-channel systems of the type offered by MEDCO, Ltd., however, difficulties remain. Particularly, in order to stay price competitive, the system component costs must be kept low. But, where component costs are cut, as for example, where a low-cost detector such as one of the superregenerative type is used in the receiver, system sensitivity is reduced. And, where receiver sensitivity is reduced, the distance the transmitter can be spaced from the receiver and still maintain control; i.e., system range, is, likewise, reduced. Unfortunately, the effect of reducing system range may be to prevent use of the remote controller in those applications where it can be particularly attractive; for example, large rooms or high ceilings commonly found in commercial or industrial buildings, or from adjoining rooms or outside residential structures.
More specifically, to satisfy the requirements of current and anticipated remote control applications, it has been found desirable to maintain system range at between 50 to 100 feet; a range which discourages use of low-sensitivity, low-cost systems. Moreover, simply increasing transmitter power to compensate for reduced receiver sensitivity may not be possible. The Federal Communications Commission (F.C.C.) maintains and enforces strict limits on the average signal power allowed to be transmitted by an r.f. remote control transmitter. This is done to avoid injury and inconvenience which may result from r.f. energy transmissions. As is well known, r.f. energy can cause skin burns, eye damage and disrupt heart pacers, as well as interfere with services such as television and telephone.